This invention relates to a tracking control device for a vehicle capable of controlling a vehicle speed by which a driving car follows a preceding car, while maintaining a safe inter-vehicle distance, and particularly to a tracking control device for a vehicle capable of accurately detecting the inter-vehicle distance between the driving car and the preceding car by tracking an image of the preceding car which the driving car follows.
The conventional tracking control device for a vehicle of this kind is disclosed in bath Japanese Unexamined Patent Publication No. 86000/1980 and 239900/1985, in which a radar device, utilizing light or electromagnetic wave is installed at the front part of a car, that detects a preceding car by monitoring the front direction of the car, calculates the relative distance to the preceding car, and controls the speed of the driving car so that the inter-vehicle distance between the driving car and the preceding car becomes a safe inter-vehicle distance. However, in the above conventional device, since the preceding car is detected by the radar device installed at the front part of the driving car, for instance, as shown in FIG. 1, in driving on a curve, a car 32 in a passing lane may enter in the detection area of the above radar device mounted on the driving car 31. Therefore, when the car in the passing lane 32 moves faster than the flow of vehicles in a driving lane, the driving car rapidly approaches the preceding car 33 in the driving lane because the driving car 31 attempts to maintain an inter-vehicle distance from the detected car 32. When the car 32 moves slower than the flow of the vehicles in the driving lane, the driving car in the driving lane may be rapidly approached by the succeeding car 34 in the driving lane.
Furthermore, since the preceding car 32 which the driving car follows detecting the inter-vehicle distance, is not identified when a plurality of cars are running, the driver does not know to which car the driving car is following, which causes anxiety to the driver.